1. Field of the Invention
The present invention relates to a spring device and, more particularly, to a spring device of a torque wrench and which is maintained straight in the torque wrench during operation.
2. Brief Description of the Prior Art
FIGS. 1 and 2 show a conventional torque wrench which includes a tube 32 with a first end into which a shank 53 is inserted and a second end into which a block 42, a stop 45 and a bolt means 44 are inserted wherein the bolt means 44 is threadedly engaged with a threaded hole 421 defined in a rear end of the block 42. A revolving grip 40 is threadedly mounted to the second end of the tube 32 which has numbers 33 marked thereon so as to indicate the value of torque to be set. The shank 53 is pivotally inserted into the tube 32 by a first pin 31 and has a head portion 30 formed one a first end thereof which extends from the tube 32. The shank 53 has a second end with a protrusion 52 disposed transversely thereto. An actuating member 50 is securely received in the tube 32 by a second pin 51 and has a roller 54 mounted to the second pin 51. A spring 43 is biasedly disposed between the actuating member 50 and the block 42. When using the torque wrench, a user rotates the revolving grip 40 to push the block 42 to depress the spring 43 until a front edge of the revolving grip 40 is in alignment with a number 33. When a torque having the same value as the number 33 set is transmitted from the wrench, the torque will force the roller 54 rapidly sliding across the protrusion 52 so that a sound is produced to notify the user the desired torque is achieved.
However, the spring 43 is found to be curved in the tube 32 when being depressed by the block 42 as shown in FIG. 2, this results the torque to be set is different from the number 33 alignment with the front edge of the revolving grip 40 because the positions of the numbers 33 are determined under a condition when the spring 43 is maintained straight when being depressed. Therefore, there has been at most 4% error when using the conventional torque wrench.
The present invention intends to provide an improved spring device of a torque wrench to mitigate and/or obviate the above-mentioned problem.